workaround: leak Vulkan instance & device

comments document why this is needed. closes #59

lsfg-vk-backend/include/lsfg-vk-backend/lsfgvk.hpp

@@ -129,4 +129,11 @@ namespace lsfgvk::backend {
         std::vector<std::unique_ptr<Context>> m_contexts;
     };
 
+    ///
+    /// Make all lsfg-vk instances leaking.
+    /// This is to workaround a bug in the Vulkan loader, which
+    /// makes it impossible to destroy Vulkan instances and devices.
+    ///
+    void makeLeaking();
+
 }

lsfg-vk-backend/src/lsfgvk.cpp

@@ -32,6 +32,7 @@
 #include <exception>
 #include <filesystem>
 #include <functional>
+#include <iostream>
 #include <memory>
 #include <optional>
 #include <stdexcept>
@@ -77,6 +78,12 @@ namespace lsfgvk::backend {
         /// @return the RenderDoc API
         [[nodiscard]] const auto& getRenderDocAPI() const { return this->renderdoc; }
 #endif
+        // Movable, non-copyable, custom destructor
+        InstanceImpl(const InstanceImpl&) = delete;
+        InstanceImpl& operator=(const InstanceImpl&) = delete;
+        InstanceImpl(InstanceImpl&&) = default;
+        InstanceImpl& operator=(InstanceImpl&&) = default;
+        ~InstanceImpl();
     private:
         vk::Vulkan vk;
         ShaderRegistry shaders;
@@ -634,3 +641,24 @@ void Instance::closeContext(const Context& context) {
 }
 
 Instance::~Instance() = default;
+
+// leaking shenanigans
+
+namespace {
+    bool leaking{false}; // NOLINT
+}
+
+InstanceImpl::~InstanceImpl() {
+    if (!leaking) return;
+
+    try {
+        new vk::Vulkan(std::move(this->vk));
+    } catch (...) {
+        std::cerr << "lsfg-vk: failed to leak Vulkan instance\n";
+    }
+
+}
+
+void backend::makeLeaking() {
+    leaking = true;
+}

lsfg-vk-layer/src/entrypoint.cpp

@@ -232,8 +232,8 @@ namespace {
         // destroy layer info
         // NOTE: there's no real way of unloading the layer without a deconstructor.
         // multiple instances just aren't common enough to worry about it.
-        // NOTE2: it doesn't really matter anyways, because the myvkDestroyDevice code
-        // freezes the entire thing anyways.
+        // NOTE2: this IS a memory leak, because the VkInstance inside of root->backend
+        // cannot be destroyed, due to a Vulkan-Loader limitation/bug.
         delete layer_info;
         layer_info = nullptr;
     }

lsfg-vk-layer/src/swapchain.cpp

@@ -104,6 +104,8 @@ Swapchain::Swapchain(const vk::Vulkan& vk, backend::Instance& backend,
                 backend->closeContext(ctx);
             }
         );
+
+        backend::makeLeaking(); // don't worry about it :3
     } catch (const std::exception& e) {
         throw ls::error("failed to create swapchain context", e);
     }